Cancer is the second leading cause of death in the United States. In 1998, 564,800 Americans are expected to die of cancer (American Cancer Society). The National Cancer Institute estimates overall annual costs for cancer to be $107 billion. Thirty-seven billion dollars per year is spent in direct medical costs, with over half of the direct medical costs directly related to treatment of breast, lung, and prostate cancers.
Breast cancer is the second leading cause of cancer death in women, and the leading cause of cancer death among women age 40 to 55. In 1998, about 43,900 people (both men and women) are expected to die from breast cancer.
Chemotherapy is a common treatment for breast cancer, and a combination of anticancer drugs has proven more effective than a single drug. The effects of most chemotherapeutic agents are most profound on rapidly growing cells, such as cancer cells, although few agents have been found that exhibit a selective toxicity to cancer cells alone. The commonly known side effects of chemotherapy arise due to the cytotoxic effects of chemotherapeutic agents on normal cells.
The most commonly used chemotherapy combinations are cyclophosphamide, methotrexate, and fluorouracil (CMF) and cyclophosphamide, doxorubicin (Adriamycin), and fluorouracil (CAF). Recent data suggests that paclitaxel may also be useful for breast cancer treatment. Chemotherapy usually lasts three to six months and is given in cycles, with each period of treatment followed by a recovery period. The side effects of chemotherapy depend on the type of drugs, the amount taken, and the length of treatment. Typical side effects may include nausea and vomiting, loss of appetite, loss of hair, mouth sores, and changes in the menstrual cycle. Because chemotherapy can damage the blood-producing cells of the bone marrow, patients may have low blood cell counts, which can result in an increased chance of infection (due to a shortage of white blood cells), bleeding or bruising after minor cuts or injuries (due to a shortage of blood platelets), and fatigue (due to low red blood cell counts). Potential permanent complications of chemotherapy, particularly in older women, include premature menopause and infertility. Premature menopause may contribute to the development of osteoporosis and coronary artery disease, due to failure of the ovaries to produce estrogen. Adriamycin (doxorubicin) may cause permanent heart damage, so the dose of this drug must be carefully controlled. Very rarely, certain chemotherapeutic drugs may cause acute myeloid leukemia (AML) years after treatment.
Radiation therapy may be used to reduce the size of a tumor before surgery or to destroy cancer cells remaining in the breast, chest wall, or underarm area after surgery. The main side effects of radiation therapy are swelling and heaviness in the breast, sunburn-like skin changes in the treated area and possibly fatigue, but these changes to the breast tissue and skin usually go away in 6-12 months.
Another approach to treating breast cancer is to block the effect of estrogen or lower estrogen levels, often by the antiestrogen drug tamoxifen (Nolvadex). It is taken daily in pill form, for at least two years and usually for five years. Some studies have shown a slight increase of early stage endometrial cancer among women taking tamoxifen, with the risk increasing if the drug is taken for more than five years.
Megestrone (megace) is another drug used for hormonal treatment of advanced breast cancer, usually for women whose cancers do not respond to tamoxifen. Progestins (produced in the ovaries) or androgens (male hormones) also may used to treat advanced breast cancer. Side effects include fluid retention (progestin) and development of masculine characteristics (androgens).
Oophorectomy (surgery to remove the ovaries) may be used in pre-menopausal women to eliminate the body's main source of estrogen.
Prostate cancer is the second leading cause of cancer death in men. In 1998, 39,200 men are expected to die of prostate cancer in the United States. Recent advances in prostate cancer research include the discovery of a gene linked to prostate cancer, HPC1.
Treatment for prostate cancer follows a similar course to that taken in the treatment of breast cancer. Chemotherapy and hormone therapy figure prominently in the therapy regimen.
Chemotherapy, although helpful for decreasing the number of cancerous cells, has proven to be less satisfactory at producing remission from cancer than had been anticipated. The side effects of chemotherapy have made long-term treatment an unpleasant and harmful alternative. Furthermore, drug resistance to chemotherapeutic agents is common. A safe, effective chemotherapeutic agent, particularly one which could be combined with the chemotherapeutic agents presently available, would increase effectiveness of chemotherapy, while decreasing treatment time and decreasing the potential for the development of serious side effects.